Media release

From: Springer Nature

Planets located in the habitable zones of metal-poor stars may be the best targets in the search for potential life, suggests a Nature Communications paper.

High levels of ultraviolet (UV) radiation may cause genomic damage in life forms. Atmospheric oxygen and ozone protect Earth’s biosphere from harmful UV levels from the sun, but the amount of UV radiation emitted varies from star to star. Low levels of stellar UV radiation are known to lead to low planetary ozone levels, and therefore less UV protection. However, the influence of stellar metallicity, the abundance of elements heavier than hydrogen and helium in a star, on UV protection and planetary habitability is unclear.

Anna Shapiro and colleagues modelled the atmospheres of hypothetical Earth-like planets hosted by stars with a range of metallicities and found that the planets around metal-poor stars have more UV shielding, which may have implications for potential life. Although metal-rich stars emit substantially less UV radiation than metal-poor stars, the surface of their associated planets are exposed to more intense UV radiation. The authors suggest that planets orbiting metal-rich stars are less suitable for life despite receiving relatively less UV radiation.